Method of control of electric motors.



2 SHEETS-SHEET 1.

PATENTED DEC. 81, 1907.

d d m i R H. D. JAMES.

METHOD OF CONTROL OF ELECTRIC MOTORS.

APPLICATION FILED MAY 6, 1907.

INVENTOR inn is m

ATTORNEY No. 875,583. PATENTED DEC. 31', 1907.

-' H. D. JAMES.

METHOD OF CONTROL OF ELECTRIC MOTORS.

v urmouxon rub-1m my 6, 1907.

2 SHEETS-SHEET 2.

WITNESSES: 8 INVENTOR.

zfityy 39 B AT ORNEYIN FACT.

To all whom it may concern:

s'rnTEs PATENT FFICE. v

HENRY 1). JAMES, OFPITTSBURG, PENNSYLVANIA, ASSIGNOR 'ro WESTINGHOUSE ELECTRIC &

MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

'IETKOD or CONTROL or ELECTRIC; MOTORS.

Patented Dec. 31, 190').

Application flied Kay 6' 1907- Sarial No. 372.138

Be it known that I, HENRY D. JAMES, a

. citizen of the United States, and a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Methods of Control of Electric Motors, of which the'following is a specification.

My invention relates to methods-of controlling electric motors, and .particularly to methods in which the motor armature is connected successively to circuits of different voltage.

. The Object of m invention is to provide a method Of contro whereby a motor may be suddenly disconnected from a circuit of high voltage and immediately connected to a circuit of low voltage, without causing injury thereto.

- It isa common practice to effect speed variation of, electric motors by connecting them successively to circuits of different voltage, resistance being usually inserted in 'serieswith the armature and gradually removed for each voltage step. In order that an excessive flow of current through the armature may be prevented when stepping from a low voltage to a high voltage, the

' voltage changes have heretofore been made Without interrupting the armature circuit, this being done by connecting the motor armature in series with a resistance between the conductors of the high voltage circuit while the armature still remains connected to the low voltage circuit, and in then disconnecting the motor from the low voltage circuit. In the systems heretofore employed, however, the motor cannot be disconnected from the high voltage circuit when operating at a speed in excess of that which may be obtained upon the low voltage circuit, and re-connected to the low voltage circuit Without danger'of injuring the motor because the electromotive force generated by the motor may be in excess 'of that of the'low voltage circuit.

Figure l of theaccompanying drawings is a diagrammatic view of a system of control in which my invention is practiced, and Fig. .2 illustrates, diagrammatically, the main circuit connections for each position of the controller.

The system comprises a-plurality of se arately' actuated switches 1, 2, 3, 4, 5, 6 ans 7 whereby a motor armature 8 may be conmaster controller occupies the nected to conductors 9, 10 and 1i ofa multiple-voltage circuit and the amount of a resistance 121314-'--15 in series with the motor armature may be governed. The switches 1 to 7, inclusive, are provided, re-

spectively, with operating or controlling magnet windings 16, 17, 18, 19, 20, 21 an 22, corresponding terminals of the windings .18, 19, 20 and 21 being connected, respectively, to terminals of the resistance sections 12, 13, 14 and 15. The circuits of the magnet windings are overned automatically by means of interloc 'ng switches that are associated with the switches 1 to 7, inclusive, and manually by means of a master controller, that comprises movable conducting segments 23, 24 and 25 and stationary con-- tact terminals 26 to 37, inclusive, with which the conducting segments may be caused to en age along positlon-indicatmg lines a to Z, inc usive. The movable segment 23 and the stationary terminals 27 to 30 of the master controller are provided for the purpose of governing the amount of a resistance 38 that is included in circuit with field magnet winding 39 of the motor.

The operation of the system maybe best understood from a detailed description of the circuits corresponding to several of the positions of the master controller. When the OSltiOD a, a circuit is established by way of evices hearing reference characters 9, 26, 23, 27, 39 and 10, the field magnet windin 39 of the motor being thereby energized. other circuit is also established by way of devices 9, 26, 23,

25, 37, 40, 41, 42, 17 and 10. Switch 2 then closes and connects the motor armature 8 in series with the resistance l2 el3l4-l5 between the low voltage circuit 910.'

When the switch 2 'closes, a member 43 bridges terminals 44 and 45 and a circuit is thereby established through the devices 9,

'26, 23, 25, so, 45, 43, 44, 1s, 12, 2 and 10.

ance section 12 alls elow a predetermined Another circuit will thereupon be established because of the raislng of the value.

bridgingsmember 47 into engagement with termina 48 and 49, the said circuit continuing from the terminal 36 through the devices I contact terminals 54 andv 55 49, 47, 48, 19, 13, 3, 2 and 10. The magnet winding 19'will become sufliciently energlzed to effect closure of the switch 4 when the counter electromotive force of the motor at tainsa predetermined value. It will be seen that, when the'switches 3 and 4 are closed,

resistance sections 12 and 13 will be shunted.

successively, leaving only resistance sections 14 and 15 in series with the motor armature.

When the master controller occu ies the position 6, another circuit is establis ed'through the devices 9, 26, 23,- 25, 35, 50, 51, 52, 20, 14, 4, 2 and 10, thebridging member 51 havpreviously been caused to engage termina s 50 and 52, by reason of the closing of the switch 4; The switch 5' will, in turn, be

. position a, a circuit is established through the devices 10, 32, 24, 33, 58, 56, 57, 59,- 60, 61, 22 and 11, it being observed that thecircuit is connected between'the low volta e conductors 10 and 11, whereas the contro ling ma nected etween low volta e conductors 9 and 10. The magnet win ing '22 then becomes energizedjto close the switch 7 and ,therebz connect the motor armature 8. di-

rectly tween low voltage conductors 9, and 10, with no resistance in circuit. of the switch 7 to closed position causes the bridging member 41 to be moved-out of en' gagement with terminals 40 and 42 and into engagement with terminals 63 and 64, the bridging member 65 bein also moved out of engagement with, termina s66 and 67'. The

I position of the brid member 65, when the switch 7 is close prevents energi zation of the ma et' winding 21 ofv the switch 6. When the i 'idging member 41, is raised it interruplts the circmt oithe magnet winding 17 i and t us causes theswitch 2 to open, the circuit of magnet winding 18 being also. interru ted onaccountpf the lowering of the brldging member 43. Switch 3 is thereby. permitted'to open and the circuit of magnet winding 19 is interrupted by the lowering of the bridging member 47. In like manner,

. the circu t of the magnet windin 20 is interrupted by the movement of t e bridg ng member 51 when the switch 4 opens, and the switch 5 is thus caused to open. When the switch 2 opens, bridging member 68 engages contact terminals 69 and 70 so as to mam? tain the circuit of the magnet windin 22 independent of the interlocking switc 56- et windingswere previously con- Movement and 11. come sufiiciently ener 'z-sd to effect closure of the switch 3 when t e lrop of potential in 57-58, in order that opening of the switch 5 n maynot interrupt the same and cause opening of the;switch 7, the said circuit, as maintained, beingthrough devices 10, 32, 24, 33, 70, 68, 69, 59, 60, 61 22 and 11.

i As the master controller is moved through the succeeding positions d, .e and f, gradually increasing amounts of the resistance 38 are included in the circuit of the field magnet winding 39, the armature circuit remaining undisturbed, althou h con-tact terminals 35, 36 and 37 become disengaged from the conducting segments 25, and contact terminal 34 engages-conducting se ment 24, because no new circuits are estab 'shed through the controlling magnet windings of theswitches.

However, as themaster controller is moved to the position 9, conducting segment 24 is brou ht' into engagement with contact termina 31 anda circuit is thereby established through devices 1.0, 32, 24, 31, 63,41, 64,- 16

. and 11, it being noted. that, after said circuit is established, the contact terminal 33 becomes disengaged from the conducting se ment 24 and the circuit of the ma et winr ing 22 is interrupted, the switch 7 i: permitted to open. The switch 1 is closed by the winding 16, when energized, and one terminal of, the resistance section 12 is thereby connected toconductor 11. Thus, in pass-,

ing from position f toposition g of the master controller, the motor armature 8' is first coning then s nected between conductors 9 and 10,'then the I resistance 1213'1415 is connected between conductors 10 and 11, and finally the switch 7 opens to remove the common connection of the resistance and motor armature with conductor 10. When the switch 1 is closed,

bridging member 71' is caused to enga e terminals 72 and 73 and a, circuit isestab ished forthe magnet winding 16 independently of the interlocking switch 634164 throu h devices 31, 74, 75, 7 72, 71 and 73. T e bridging member 77 is also caused to engage terminals 78 and 79 when the switch 1 is closed and a circuit is established through devices 10, 32, 24, 36,- 79, 77, 7s, 1s, 12, 1

The magnet winding 18 willbethe resistance section 12 decreases to a predetermined value, it being noted that the said winding is now connected. between one terminal of the resistance section 12 and the conductor 10,whereas,wh'en the motor armature was connected between conductors 9 and lO, the said windin 'was' connected between one terminal of t e resistance section 12 and the conductor'9. Thus, if the difference of potential between. the conductors 9 and 10 and that between theconductors 10 and 11 are approximately the same, as will usually be the case, the voltages applied to the circuit of the winding 18 will be approximately the same. whether the motor armamature circuit.

ture is connected to a high or to a low voltage circuit, and'the magnet winding 18 will become sufliciently energized to effect closure of the'switch 3 at the same current value or dro of potential in the resistance section 12 for 0th voltages that are applied to the arthe resistance section 12 and raises the bridging member 47 into engagement with contact'terminals, 48 and 49, thereby establishing a circuit from the contact terminal 36 throu h devices 49, 47, 48, 19, 13, 3, 1 and 11. en the drop of potential over the resistance section 13 decreases to'a predetermined value the -=winding 19 will become sufliciently energized to effect closure of the switch 4, resistance section 13 being thereby *When the switch 4 closes, the bridgin I member 51 is raised into engagement'wit terminals 50 and 52, so that, ifthe master controller is then moved to the osition "if, a circuit will be established throug devices 10, 32,24, 35, 50, 51, 52, 20,14, 4, 1 and 11, the switch 5 being closed to effect shuntin of the resistance section 14 when the drop ('1 pctential over the resistance section 14 decreases. to a predetermined value. Closing the switch 5 raises bridging member 53 into engagement with terminals 54 and 55, and a circuit is thereupon established through devlces 10, 32,24, 34, 66, 65, 67, 55 53, 54, 21,

6, 15, 5, 1 and 11. The magnet windin 21 will become sufliciently energized to eect closure of the switch 6 when the dropof potential over the resistance. section 15 decreases to a predetermined value, and bridging member 75 is thereu on raised'out of en- .gagement with termina s 74 and 76. The

clrcuit of the magnet winding 16 of the switch 1- is thereb interrupted and the switch 1 opens. T e switches 3, 4 and 5 also open in succession, leaving the motor armature connected directly between the conductors 9 and 11 by means of the switchv 6. U on closing the switch 6, bridging member '60 is raised out of engagement with terminals 59 and 61, energization of the ma net winding 22 of the switch 7 a being t ereb ,prevented while the switch 6 remains c osed, and the member 60 is caused to engage contact terminals 83 and 84, a circuit being thereby established for theswitch magnet 21 between the terminal 67 and the winding 21 independently of that previously established upon the closing of the switch 5 and subsequently interrupted upon the opening of the said switch by means of interlocking switch 535455. The switch .6 alone remains closed through the succeeding positions 1', 7c and l of the master controller, in moving through which positions the amount of the resistance 38 included in circuit with the field magnet winding 39 is adjusted.

Closing the switch 3 shunts the circuit 9 -11, the counter electromotive force thereof will usually be greater than the 910 and serious injury may, consequently, be done the motor 1f the armature is suddenly disconnected from the high voltage circontroller to be returned to the position (1. 1n theposition g, the

tion f. Although,.in the latter position, the segment 24 engages contact terminal 33, the

cuit and immediately connected to the lownected to the owevoltage circuit, resistanceis readily understood by su posin the master-- om t e positiong switch 6 is alone closed, and also in the posi-= 'When the motor armature isconnected to electromotive force of the low voltage circuit 7' 7.

effected without interrupting the armature 'an'dwhen the motor armature is disconnected 7 circuit of the magnet winding 22 of the switch 7 is interrupted because bridging member 60 does not en age terminals 59 and 61.. In passing from the position f to the position 0, segment 25 is first caused to engage contact terminal 37 and a circuit is thereby established ance 1 2 1'31415 is connected between next becomes disengaged from contact ter minal 34 and the circuit of ma net winding 6 being thereby permitted to open, leaving the motor armature connected between conductors 9 and 10 with the resistance 1213 controller then occupies the position (i, the switches 3, 4, 5, and 7 will close in succession, thereby removing the resistance 12-13 14'1 5 from the circuit of the motor armature, or, if the master controller occu ies the position b, on]

motor wili again accelerate to a speed corresponding to the position of the master controller. Thus it 1s seen that, in reducing the voltage applied to the armature circuit, the

circuit with the resistance in series therewith, and then it is disconnected from'the highvoltage circuit, the resistance serving first to prevent short-circuiting of the supply circuit, and then to protect the motor from lnjury in case the .electromotive force generated thereby exceeds that of the low-voltage circuit.

1 claim as my invention:

1. The method of operating an electrical translating device which consists in connecting the same successively to supply circuits the conductors 10 and 11. The segment 24,

through devices9, 26, 25, 36, 37,40, 41,42,17' and 16. Energization of the magnet winding 17 causes theswitch 2 to clo'seand the resist V 21 of the switch 6 is interrupte the switch 1415 in series therewith. If the master switches.3,4and 5W1 close. The

armature 1s first connected to the low-voltage of decreasing voltage while stillmaintaim'ng the circuit of the device, and in introducing resistance in series with the device between the same and the low-voltage supply circuit when effecting a reduction in voltage.

2. The methodof o crating an electrical translating device whic consists in connecting the same to a circuit of high voltage, connecting the device to a circuit of lower voltage and in series with a resistance while still maintaining the connection of the device with the high voltage circuit, and breaking the said connection with the high voltage circuit. a

3. The method of changing the connection of a translating device from a high voltage circuit to a circuit of lower voltage which consists'in connecting a resistance between amass one conductor of the low volt e circuit and one terminal of the device, an breakin the ing the same to a high voltage conductor,

connecting a resistance between the high voltage conductor and a lower voltage conductor and breaking the connection of the device and the resistance with the high voltage condoctor. 1 In testimony whereof, I have hereunto subscribed my name this 29th da of A ril, 1907.

HENRi D- AMES. Witnesses:

Ross W. COPELAND, BIRNEY HINES.

crating an electrical 4 

